Process for electrolytically producing peroxid of hydrogen.



Patented Mar. 30, 1909.

G. TEICHNER. PROCESS FOR ELEGTROLYTIGALLY PRODUCING PEROXID OF HYDROGEN.

APPLICATION FILED DEG. 2a, 1905., 91 6,900.

y%ilg7f%w Zhemes WW4 GUSTAV TEICHNER, OF NUREMBEBG, GERMANY.

PROCESS FOR ELECTROLYTICALLY PRODUCING PEROXID OF HYDROGEN.

Specificationof Letters Patent.

' Patented March so, 1909.

Application filed December 28, 1905. Serial No. 293,677.

To all whom it may concern: e

Be. it known that I, G-UsTAvTEIeHN R, a

subject of the Emperor of Austria-Hungary,

residing at No. 54 Gugelstrasse, Nuremberg,

\ Bavaria, Germany, have invented new and useful Improvements in the Process for Electrolytically Producing Peroxidof Hydrogen, of which the following is a description.

The. present invention consists of a process for electrolytically producing peroxid of hydrogen.

As is well known peroxid of hydrogen cannot be obtained in large quantities by means of electrolysis, because it is decomposed at the anode, oxygen being developed. It is also known that persulfuric acid like its salts, which may be easily obtained by electrolysis is converted by 'strong acids first into the so-called Ca-ro-acir and then yield peroxid of hydrogen. This reaction, which would permit the indirect electrolytical production of peroxid of hydrogen, has hitherto not been adapted for employment in the technical production of the same, because no one had succeeded in isolating the peroxid of hydrogen from its solution in sulfuric acid. The conversion can only be effected quickly and properly in strong acid solutions, and since, in addition to this, sulfuric acid is developed in the reaction itself, a solution is finally obtained which may contain up to 80% of sulfuric acid, with relatively small quantities of peroxid of hydrogen. The difficulty is due to the fact that peroxid of hydrogen reacts with sulfuric acid to generate a body of uncertain composition, though possibly represented by H 8 0 which is generally known as Caro acid, and the quantity of which depends on the temperature and acidity of the solution. Now, peroxid of hydrogen and the Caro-acid easily act on each other generating oxygen and the slightest uantity of any catalytic agent will be su cient to effect mutual decomposition. According to experiments by Price and Friend (J own. Chem. Soc. London, vol. 95, p. 1526) the sensitiveness of such solutions with regard to catalytic agents is much greater than that of peroxid of hydrogen solutions alone, and on warming the same, an intense generation of oxygen generally takes place. For this reason the conversion of the persulfuric acid into peroxid of hydrogen has always been ac- .ing sulfuric acid by companied by a very considerable loss of oxygen, and it has hitherto been quite impossible to separate the peroxid of hydrogen from the sulfuric acid. The methodordinarilyemployed for purifying peroxid of hydrogen by precipitating the sulfuric acid with baryta etc., is of course quite impracticable in the present case owing to the larg quantities of sulfuric acid.

Now my experiments have shown that the decomposition of the above named solutions. may be almost entirely avoided by avoiding any .trace whatever of catalytic agents and that if pure solutions are em ployed, not only will the conversion of the persulfuric acid into peroxid of hydrogen take place more advantageously, but it will even be possible to separate the peroxid of hydrogen produced from the accompanyvarious methods and practically without oss.

Regarding the conversion of persulfuric acidinto hydrogen peroxid, Elbs has found (Zeitschmft der Elektrochemie' Z, page 471) that at ordinary room temperature it takes place very slowly and is accompanied by considerable loss of oxygen. Elbs accelerated the conversion by heating, but this in volved the decomposition of about 80% of the persulfuric acid, oxygen being developed. I, on the other hand, have succeeded in converting a solution of 21-gr. of persulfuric acid in 100 cubic centimeters of a sulfuric acid of 1.4 specific gravity, absolutely free from catalytic agents at 50 C. in 45 minutes and with a loss of only 3% of the oxygen into an equivalent solution of peroxid of hydrogen.

For the purposes of the presentspecificm tion I use the expression ersulfuric acid is converted into peroxid 0 hydrogen for the sake of brevity, to be uite exact, it would be necessary to continually repeat that the yielding su furic acid and peroxid of hydro gen. 1

The peroxid of hydrogen formed may be separated from the accompanying large quantities of sulfuric acid in various ways. Extraction with various solvents and distillation have proved to be the most suitable way.

The extraction is advantageously effected by means of sulfuric or acetic ether, since these leave the sulfuric and (are acids almost entirely undissolved and are not noticeably attacked by them. By employersulfuric acid is decomposed,

. j ti ousl working extracting a paratus on the oxhlet rinciple or similar ones, the peroxid ofhy rogen'can be completely extracted with relatively small quantities of ether, and 1n this manner It is obtained in the form of pure and absolutely stablesolutions of any desired concentration.

Distillation when employed should be carried out asquickly as possible andat the 10 lowest possible temperature. It is advantageous to Work in vacuo and the driving out of the peroxid of hydrogen may be accelerated by feeding in a currentof steam or of anindifferent gas such as ether va or. The loss of. oxygen during the distil atidn depends on the degree of purity of the solutions.

hile in the presence of catalytic agents a lar e proportipn of the eroxid of hydro en is decomposed during t e course of the istillation, it can be forced over into the receiver entirely with'out'the least decom osition when distilling ure solutions. If the distillation is-propery conducted, no sulfuric acid will pass over and consequently the eroxid ofhydrogen will be obtained in an a solutely pure and therefore very stable employed as metal anode dissolves, and this latinum owing to its great catalytic effect, unfavorably influences, the yield of peroxid of hydrogen. It has been found that this disadvantage may be avoided by electrol tically preci itating the platinum out of t e solution. his recipitation may be combined with the main electrolysis by placing an auxiliary cathode in the anode chamber through which a small fraction of the main current should be allowed to pass;

Instead of the electrolysis, the platmum may be eliminatedv by means of suitable" chemical operations or by distilling the ulfuric acid. In this manner solutions obtained which are eminentl suitedfor the production ofperoxid ofydrogen, and enable the same to be obtained practically without loss.

sulfuriceacid has been converted into peroxid of hydrogen before carrying out the distillation of the latter. -The ersulfu'ric acid solution obtained by electro ysis or by the action of sulfuric acid on ersulfates or in any other way, may be lstilled at once. Since at a distilling temperature of for instance 60C. and owing to the continuous It has further been found thatit is not necessary to wait until the perremoval of the peroxid of hydrogen for med,

from persulfuric acid ma be combined with the extraction of the former by means of the above named dlssolvmg agents;

The solutions freed from the peroxid of hydrogen in the manner described or in other ways may 'be subjected again to electrol tic oxidation, after having been brought bac to the original strength so that the persulfuric acid will simply serve as a transmitter of oxygen and the peroxid of hydro en will be formed 6y an uninterrupted cyc ic process by indirect oxidation of water.

In restoring the, ori inal strength of the acid, water is added and in the next electrolysisghis water is converted into hydrogen per- OX1 Instead of persulfuric acid other'electros lytically obtainable combinations of the nature of -per acids may be emplo ed analogously as oxygen transmitters. it is'for instance known that the percarbonates and perborates capable of electrolyzation when dissolved inwater, decompose, in forming peroxid of hydrogen. 4 If this latter is removed from the solution by suitable methods for instance by extraction with ether, the conversion will go -on to the end and the solutions I freed from the peroxid of hydro en may be subjected again to electrolysis. n this way also peroxid of hydrogen may be obtained by indirect oxidation of water.

In the accompanying illustration, I have shown, more or less diagrammatically, tain a paratus adapted for use in t e scribed process. v

In this showing :Figure 1 is a view in vertical section of a cell containing an auxiliary cathode; and Fig. 2 is a view, partly in/elevation and artly in yertical section, of a device adapted or use in distillation.

In Fig. 1, A is. a platinum anode; K is a cathode, which may be made of graphite or other suitable material; K is an auxiliary cathode, which may also be made of graphite; D is a diagram and R is a, regulating rheostat; L designates the electrolyte and MM temperature re ulating coils.

In Fig. 2, O is an 0' or water bath; F is a still G a condenser and E a receiver'provided with a valved pipe B through which a vacuum connection may be made.

' The distillation apparatus is advantaeously made of, or lined with, glass, 'porcefain, enameled steel or other resistant material to avoid decomposing the hydrogen peroxid.

- I claim as my invention .1. A process for producing peroxid of hydrogen, which conslsts in forming peroxid'of hydrogen from persulfuric acid and subseuentl separating the peroxid of hydrogen rom t e sulfuric acid produced.

2. A process for producing peroxid of hydrogen, which consists in forming peroxid of furic acid produced.

3. A process for producing peroxid of hydrogen, which consists in forming peroxid of hydrogen from persulfuric acid practically free from catalytic nts at a temperature a e of not less than and isolating the per oxid of hydrogenfro'm the accompanying sulfuric acid by extraction.

4. A process for producing peroxid of hydrogen, which consists in subjecting solutions of persulfuric acid practically free from catalytic agents, in a heated condition, toap. extracting process, during such extraction gradually forming eroxid of hydrogen and separating out the atter as it is formed.

5. A process for producing p'eroxid of hydrogen which consists of forming peroxid of hydrogen from persulfuric acid practically free from catalytic agents and isolating the peroxid of hydrogen from the accompanying sulfuric acid by distillation.

6. A process for producing eroxid of hydrogen, which consists in dist' a solution of persulfuric acid practically free from catalytic agents while continuously producing peroxid of hydrogen therein, thus separating out the peroxid' of'hydrogen as it is formed. 7. A process of producing peroxid of hydrogen which consists in electrolytically 1preparing persulfuricv acid, removing disso anode metal, forming p'eroxid of hydrogen from the purified acid and separating such peroxid from the sulfuric acid produced;

8. A process of producing peroxid of hydrogen which consists in electrolytically forming persulfuric acid, forming hydrogen eroxid therefrom with production of sulved furic acid and re-forming persulfuric acid continuous cycle.

' 9. A process of producing peroxid of hydrogen which consists in electrolytically reparing persulfuric acid, during electro ysis eliminating any dissolved anode metal, forming hydrogen peroxid from the purified acid and isolating such eroxid.

10. A rocess of pro ucing peroxid of hydrogen W ch consists in electrolytically re paring a per acid, forming peroxid of hy rogen therefrom with reformation of the original acid and reforming the per acid from such acid electrolytically in continuous cycle.

In testimony whereof I afiix my signature in the presence of two witnesses.

GUSTAV TEI'CHNER.

from such sulfuric acid, electrolytically'in Witnesses:

LUDwIe SGUMINGER, KARL KOTTMUNN. 

